From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E3AF3C433EF for ; Fri, 1 Oct 2021 12:56:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C094A61AA7 for ; Fri, 1 Oct 2021 12:56:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231591AbhJAM6C (ORCPT ); Fri, 1 Oct 2021 08:58:02 -0400 Received: from mail.kernel.org ([198.145.29.99]:60952 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231434AbhJAM6B (ORCPT ); Fri, 1 Oct 2021 08:58:01 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 1BAB161A8E; Fri, 1 Oct 2021 12:56:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1633092977; bh=OCYsuTxAX9XCeJG6jmvCduDTUJshbOFoeOK6I+5rb4E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YJJ9+qhO0H/ejsPIcPfwLqhD16oy2FXrOSVax6qKxpKR27f+2tRoznc/n/+iVp69y k/PC+7ZPNBYnwrsZxizs2QsZ7GRwMVQooc8RNEd8bL3fS+hXAiDUzh76HkCTvQDgDF qf4BXvCa7H8nE+fjUfN61MQYyOgQcERGYyW1AcyZE5ngwxQAeag1Z9j1rLWrK9B13M d7I7vHHKN+bPeUc5GjEkzusCijasKmw0xIZJHO4jjl+LNNA9zPgEqrjNcPESOV6dzY Y/XqVj0YJ9b91y8sJZ5qV4ttqAPu1x8y4oVNDSARXUm1p0Ppy+V41Qi/r/AAQOhPfH 9ap9SyN7PkReg== From: SeongJae Park To: akpm@linux-foundation.org Cc: SeongJae Park , Jonathan.Cameron@Huawei.com, amit@kernel.org, benh@kernel.crashing.org, corbet@lwn.net, david@redhat.com, dwmw@amazon.com, elver@google.com, foersleo@amazon.de, gthelen@google.com, markubo@amazon.de, rientjes@google.com, shakeelb@google.com, shuah@kernel.org, linux-damon@amazon.com, linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 1/7] mm/damon/core: Account age of target regions Date: Fri, 1 Oct 2021 12:55:58 +0000 Message-Id: <20211001125604.29660-2-sj@kernel.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20211001125604.29660-1-sj@kernel.org> References: <20211001125604.29660-1-sj@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org DAMON can be used for data access pattern aware memory management optimizations. For that, users should run DAMON, read the monitoring results, analyze it, plan a new memory management scheme, and apply the new scheme by themselves. It would not be too hard, but still require some level of effort. For complicated cases, this effort is inevitable. That said, in many cases, users would simply want to apply an actions to a memory region of a specific size having a specific access frequency for a specific time. For example, "page out a memory region larger than 100 MiB but having a low access frequency more than 10 minutes", or "Use THP for a memory region larger than 2 MiB having a high access frequency for more than 2 seconds". For such optimizations, users will need to first account the age of each region themselves. To reduce such efforts, this commit implements a simple age account of each region in DAMON. For each aggregation step, DAMON compares the access frequency with that from last aggregation and reset the age of the region if the change is significant. Else, the age is incremented. Also, in case of the merge of regions, the region size-weighted average of the ages is set as the age of merged new region. Signed-off-by: SeongJae Park --- include/linux/damon.h | 10 ++++++++++ mm/damon/core.c | 13 +++++++++++++ 2 files changed, 23 insertions(+) diff --git a/include/linux/damon.h b/include/linux/damon.h index 755d70804705..3e8215debbd4 100644 --- a/include/linux/damon.h +++ b/include/linux/damon.h @@ -31,12 +31,22 @@ struct damon_addr_range { * @sampling_addr: Address of the sample for the next access check. * @nr_accesses: Access frequency of this region. * @list: List head for siblings. + * @age: Age of this region. + * + * @age is initially zero, increased for each aggregation interval, and reset + * to zero again if the access frequency is significantly changed. If two + * regions are merged into a new region, both @nr_accesses and @age of the new + * region are set as region size-weighted average of those of the two regions. */ struct damon_region { struct damon_addr_range ar; unsigned long sampling_addr; unsigned int nr_accesses; struct list_head list; + + unsigned int age; +/* private: Internal value for age calculation. */ + unsigned int last_nr_accesses; }; /** diff --git a/mm/damon/core.c b/mm/damon/core.c index d993db50280c..3efbe80779db 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -45,6 +45,9 @@ struct damon_region *damon_new_region(unsigned long start, unsigned long end) region->nr_accesses = 0; INIT_LIST_HEAD(®ion->list); + region->age = 0; + region->last_nr_accesses = 0; + return region; } @@ -444,6 +447,7 @@ static void kdamond_reset_aggregated(struct damon_ctx *c) damon_for_each_region(r, t) { trace_damon_aggregated(t, r, damon_nr_regions(t)); + r->last_nr_accesses = r->nr_accesses; r->nr_accesses = 0; } } @@ -461,6 +465,7 @@ static void damon_merge_two_regions(struct damon_target *t, l->nr_accesses = (l->nr_accesses * sz_l + r->nr_accesses * sz_r) / (sz_l + sz_r); + l->age = (l->age * sz_l + r->age * sz_r) / (sz_l + sz_r); l->ar.end = r->ar.end; damon_destroy_region(r, t); } @@ -480,6 +485,11 @@ static void damon_merge_regions_of(struct damon_target *t, unsigned int thres, struct damon_region *r, *prev = NULL, *next; damon_for_each_region_safe(r, next, t) { + if (diff_of(r->nr_accesses, r->last_nr_accesses) > thres) + r->age = 0; + else + r->age++; + if (prev && prev->ar.end == r->ar.start && diff_of(prev->nr_accesses, r->nr_accesses) <= thres && sz_damon_region(prev) + sz_damon_region(r) <= sz_limit) @@ -527,6 +537,9 @@ static void damon_split_region_at(struct damon_ctx *ctx, r->ar.end = new->ar.start; + new->age = r->age; + new->last_nr_accesses = r->last_nr_accesses; + damon_insert_region(new, r, damon_next_region(r), t); } -- 2.17.1